Are torturers mentally ill?

Knowing that information revealed under torture is worthless - and one still continues with the torture of the suspect - what does it reveal about the torturer?

Knowing that the more a suspect was tortured, the more they tended to freeze-up and not divulge anything - what does it say about the torturer?

Knowing that - in order to stop the torturer, a suspect will say anything - even whatever the torturer wants to hear - and the torturer still continues with the treatment, what would you call such a torturer?

KNOWING THAT THE PERSON BEING TORTURED MAY ACTUALLY BE COMPLETELY INNOCENT - and HAVE HAD NOTHING TO DO WITH TERRORISM - AND ONE STILL PERSISTS WITH THEIR 'Harsh Interrogation' - WHAT DOES IT SAY ABOUT THE Torturer?

To me - this has to be a serious sign of a mental illness - when you are willing to a) Torture innocent people without giving them an opportunity to prove their guilt/innocence
b) Continue torturing them - knowing that they will say anything to stop from being tortured - even give meaningless garbage as information.